sidebar & widget column

My site is located at https://www.nfhta123.com

I would like to be able to evenly space out my three columns.
Instead of having Recent Post on the sidebar and widget column, I want to remove the content in those column and put original content. How do I remove that content?
How to I put my own content in those areas where the left and right column reside?

And how do I create individual pages that link to my navigation buttons that do not display those columns at all once a user clicks into those individual pages?

Thank you,

Kholman